Generally toothbrushes comprise a plastics material handle with a plastics material head adjoining the handle at a base end of the head, generally via a neck region, the head and handle being disposed along a longitudinal toothbrush axis, the head having bristles extending from a bristle face of the head which is an opposite head surface to a back face of the head. The direction between the bristle face and the back face being is defined as the thickness of the head. Bristles are generally distributed in bristle tufts mounted in socket holes in the bristle face, or may be fused into the head material.
Toothbrushes having a flexibly linked region in their head are known. For example WO 92/17093 discloses a toothbrush in which the head is divided into two or more segments which are flexibly and resiliently linked to each other and/or to the handle of the toothbrush. A particular form of the toothbrush of WO 92/17093 has a head which has grooves in the back face of the head, these grooves being filled with an elastomer material to modulate the flexibility of the head. The embodiments disclosed in WO 92/17093 have their grooves distributed in a generally uniform distribution over the reverse face of the head, or around the longitudinal mid point of the head, so as to enable the whole head to accommodate itself to the curved shape of the teeth. WO 96/02165 discloses toothbrushes with flexible heads similar in construction to those of WO 92/17093, and having a generally concave profile of bristle ends. DE-G 87 05 474.4 discloses a toothbrush in which the tip region of the head is hinged to a base region of the head and an operating button on the handle allows the tip region to fold relative to the base region. WO 97/24048 discloses a toothbrush in which the head is divided into two portions, having a flexible link about half way along the head.